Docs for ‘QGIS testing’. Visit http://docs.qgis.org/2.18 for QGIS 2.18 docs and translations.

Vector overlay

Clip

Description

This algorithm clips a vector layer using the polygons of an additional polygon layer. Only the parts of the features in the input layer that falls within the polygons of the clipping layer will be added to the resulting layer.

The attributes of the features are not modified, although properties such as area or length of the features will be modified by the clipping operation. If such properties are stored as attributes, those attributes will have to be manually updated.

This algorithm uses spatial indexes on the providers, prepared geometries and apply an intersection operation if the geometry isn’t wholly contained by the mask geometry.

Parameters

Input layer [vector: any]
The layer containing the features to be clipped.
Clip layer [vector: any]
The layer containing the features that are used to clip the features in the input layer.
Open output file after running algorithm
Choose whether to load the clipped layer to the map canvas once the clip operation has been completed.

Outputs

Clipped [vector]
Where to save the clipped layer. Can be saved to file, a temporary file or a memory layer.

Console usage

processing.runalg('qgis:clip', input, overlay, output)

See also

Difference

Description

This algorithm extracts features from the Input layer that don’t fall within the boundaries of the Difference layer. Input Layer Features that are partially within Difference layer feature(s) are split along the boundary of the clip layer feature(s). If any features are selected in the Input and Difference Layers, then only those features are used in the operation. If no features are selected, then the operation is performed using all features.

Parameters

Input layer [vector: any]
The layer containing the features that will be reduced.
Difference layer [vector: any]
The layer containing the features used to reduce the Input Layer.

Outputs

Difference [vector]
Where to save the difference layer. Can be saved to file, a temporary file or a memory layer.

Console usage

processing.runalg('qgis:difference', input, overlay, output)

See also

Intersection

Description

This algorithm combines features from the Input layer and the Intersect Layer, resulting in features that cover both layers’ features. Input Feature(s) that only partially lie within the other layer’s feature(s) are split along the boundary of the other layer’s feature(s). If any features are selected in the Input and Intersect Layers, then only those features are used in the operation. If no features are selected then the operation is performed using all features.

Parameters

Input layer [vector: any]
One layer containing feature(s) to be combined.
Intersect layer [vector: any]
Second layer containing the feature(s) to be combined.

Outputs

Intersection [vector]
Where to save the intersection layer. Can be saved to file, a temporary file or a memory layer.

Console usage

processing.runalg('qgis:intersection', input, input2, output)

See also

Line intersections

Description

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Parameters

Input layer [vector: line]
<put parameter description here>
Intersect layer [vector: line]
<put parameter description here>
Input unique ID field [tablefield: any]
<put parameter description here>
Intersect unique ID field [tablefield: any]
<put parameter description here>

Outputs

Output layer [vector]
Where to save the line intersection layer. Can be saved to file, a temporary file or a memory layer.

Console usage

processing.runalg('qgis:lineintersections', input_a, input_b, field_a, field_b, output)

See also

Split lines with lines

Description

This algorithm splits the lines in a line layer using the lines in another line layer to define the breaking points. Intersection between geometries in both layers are considered as split points.

Parameters

Input layer [vector: line]
Line layer containing the lines to be split.
Split layer [vector: line]
Line layer whose lines are used to define the breaking points.

Outputs

Splitted [vector]
Output layer with split lines from input layer.

Console usage

processing.runalg('qgis:splitlineswithlines', input_layer, split_layer, splitted)

See also

Symmetrical difference

Description

This algorithm creates a layer that includes all feature(s) that are in only one of the two input layers. Feature(s) that only partially lie within the other layer’s feature(s) are split along the boundary of the other layer’s feature(s). If any features are selected in the Input and Difference Layers, then only those features are used in the operation. If no features are selected then the operation is performed using all features.

Parameters

Input layer [vector: any]
One layer containing feature(s) to be compared.
Difference layer [vector: any]
Second layer containing feature(s) to be compared.

Outputs

Symmetrical difference [vector]
Where to save the symmetrical difference layer. Can be saved to file, a temporary file or a memory layer.

Console usage

processing.runalg('qgis:symetricaldifference', input, overlay, output)

See also

Union

Description

This algorithm combines the feature(s) of both layers. Features that lie partially within the other layer’s features will be split. Areas that lie within both layers will be added as new features. If any features are selected in either of the layers, then only those features are used in the operation. If no features are selected then the operation is performed using all features.

Parameters

Input layer [vector: any]
One layer containing feature(s) to be unioned.
Input layer 2 [vector: any]
Second layer containing feature(s) to be unioned.

Outputs

Union [vector]
Where to save the union layer. Can be saved to file, a temporary file or a memory layer.

Console usage

processing.runalg('qgis:union', input, input2, output)

See also